Molecular cloning, characterization, and gene expression behavior of glucocorticoid and mineralocorticoid receptors from the Chinese alligator (Alligator sinensis)

Abstract

The Chinese alligator is an endemic crocodilian species in China. We isolated and obtained the glucocorticoid and mineralocorticoid receptor genes coding from the kidney of Alligator sinensis by nested polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE). The glucocorticoid receptor (GR) gene has 2343 base pairs encoding 780 amino acids, while the mineralocorticoid receptor (MR) gene is 2958 bp in length encoding 985 amino acids. Quantitative real‐time PCR was used to detect the distribution of messenger RNA (mRNA) levels. The maximum mRNA expressions were observed in the ovary and kidney, suggesting that these receptors may be involved in basic cellular functions or stress response of alligators. Besides this, RT‐qPCR was performed to analyze the abundance of GR and MR mRNA transcripts in early embryonic development of the Chinese alligator in the kidney, liver, and heart. The mRNA levels of GR and MR at earlier stages in kidney, liver, and heart indicates that they might involve in the transcriptional regulation of early embryos and activate many precise developmental effects in fetal tissues. We also measured the protein expression in the liver embryonic developmental stages and found that the GR and MR proteins were restricted to both the nuclei and cytoplasm. The protein expression levels in the liver at different embryonic developmental stages have extremely prominent differences. Taken together, our results showed the full coding regions of GR and MR, their characteristics, and embryonic developmental mRNA and protein expressions of both genes in A. sinensis. This study could provide the necessary information for further investigating the diverse functions of GR and MR in A. sinensis.

Thyroid and Corticosteroid Signaling in Amphibian Metamorphosis

“…In lizard, CS injection accelerates egg hatching [192]. In alligator, GR expression during embryonic development suggests a potential role for CSs in tissue maturation before hatching [193]. Finally, note that both T 3 and CSs are involved in the regulation of surfactant production in reptiles, similar to that observed in other amniotes [194].…”

Interdependence of Thyroid and Corticosteroid Signaling in Vertebrate Developmental Transitions

“…It also stimulates the secretion of phosphatidylcholine in vitro in saltwater crocodile (Sullivan et al, 2002a) and in lizard bearded dragon Pogona vitticeps (Sullivan et al, 2002b). In Chinese alligator Alligator sinensis, variations of the mRNA levels for gr in kidney, liver, and heart during embryonic development suggest a potential role for GC in tissue maturation before hatching (Izaz et al, 2021).…”